I'm adding a lens flare to an illustration; which got me thinking: Are the colours of the artifacts (hexagonal/circular) which appear in a lens flares purely random, or much like a rainbow (predictable and ordered)?

I'm adding a lens flare to an illustration; which got me thinking: Are the colours of the artifacts (hexagonal/circular) which appear in a lens flares purely random, or much like a rainbow (predictable and ordered)?
